This invention relates to a method for controlling the introduction of aquatic invasive species to a new habitat by means of a vessel's ballast water. More particularly, the present invention relates to methods and apparatus for electrochemical disinfection of ballast water.
The worldwide transfer and introduction of non-indigenous species by human activities is having significant and unwanted ecological, economic, and human-health impacts. Over the last decade, studies have found that ballast water has transported invasive marine species from their indigenous habitats, and far beyond the natural spread of the respective species. Organisms ranging from microscopic viruses to shellfish and aquatic plant life have been introduced into many U.S. waterways and ports. Each year more than 79 million metric tons of ballast water is released in the United States.
The past decade has seen extensive research of a handful of ballast water treatment options and similar levels of research have been devoted to charting the spread of AIS throughout the coastal and inland waterways of the United States. Disinfection of ballast water has not been achieved to date and current practices of ballast water management have been proven to be non-effective. The only existing mitigation option is mid-ocean ballast water exchange. Ballast water exchange is difficult to quantify in practice, cannot be safely performed on all transoceanic voyages, and by current definition cannot be conducted on voyages that take place within 200 miles of shore and in waters shallower than 2000 meters deep. Many experiments have been conducted on ballast treatment technology with respect to the general disinfection of water. Systems varying from ultra violet light radiation and mechanical filtration to thermal/heat exposure have been thoroughly investigated.
Despite all the research conducted to date, little has been accomplished with the disinfection of ballast water. Ballast water disinfection methodologies are limited by general trade industry guidelines that must be followed in order for a product to be feasible in the commercial shipping industry.
One example of such a treatment is described in U.S. Pat. No. 5,816,181 which discloses a thermal treatment method for the treatment of ballast water; U.S. Pat. No. 4,384,943 discloses a method and apparatus for the electrochemical treatment of fluid; U.S. Pat. No. 6,125,778 discloses an ozone treatment method of ballast water; U.S. Pat. No. 5,804,065 discloses an electric shock apparatus for the control of zebra mussels; U.S. Pat. No. 5,871,623 discloses an electrochemical disinfection apparatus for the treatment of water; U.S. Pat. No. 5,932,112 discloses a method for the treatment of ballast water by oxygenating and deoxygenating water; and U.S. Pat. No. 4,292,175 discloses an apparatus for the electrochemical treatment of ship's black water.